System Management Bus
The System Management Bus is a two-wire interface through which simple power-related chips can communicate with rest of the system. It uses I2C as its backbone (see iicbus(4)).
A system using SMB passes messages to and from devices instead of tripping individual control lines.
With the SMBus, a device can provide manufacturer information, tell the system what its model/part number is, save its state for a suspend event, report different types of errors, accept control parameters, and return its status.
The SMBus may share the same host device and physical bus as ACCESS bus components provided that an appropriate electrical bridge is provided between the internal SMB devices and external ACCESS bus devices.
bktr(4), iicbus(4), iicsmb(4), smb(4)
.Rs The SMBus specification